Processor having accelerated user responsiveness in constrained environment

ABSTRACT

In one embodiment, a processor includes at least one core to execute instructions and a power controller coupled to the at least one core. The power controller may include a first logic to cause the at least one core to exit an idle state and enter into a maximum performance state for a first time duration, thereafter enter into an intermediate power state for a second time duration, and thereafter enter into a sustained performance state. Other embodiments are described and claimed.

TECHNICAL FIELD

Embodiments relate to power management of a system, and moreparticularly to power management of a multicore processor.

BACKGROUND

Advances in semiconductor processing and logic design have permitted anincrease in the amount of logic that may be present on integratedcircuit devices. As a result, computer system configurations haveevolved from a single or multiple integrated circuits in a system tomultiple hardware threads, multiple cores, multiple devices, and/orcomplete systems on individual integrated circuits. Additionally, as thedensity of integrated circuits has grown, the power requirements forcomputing systems (from embedded systems to servers) have alsoescalated. Furthermore, software inefficiencies, and its requirements ofhardware, have also caused an increase in computing device energyconsumption. In fact, some studies indicate that computing devicesconsume a sizeable percentage of the entire electricity supply for acountry, such as the United States of America. As a result, there is avital need for energy efficiency and conservation associated withintegrated circuits. These needs will increase as servers, desktopcomputers, notebooks, Ultrabooks™, tablets, mobile phones, processors,embedded systems, etc. become even more prevalent (from inclusion in thetypical computer, automobiles, and televisions to biotechnology).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a portion of a system in accordance with anembodiment of the present invention.

FIG. 2 is a block diagram of a processor in accordance with anembodiment of the present invention.

FIG. 3 is a block diagram of a multi-domain processor in accordance withanother embodiment of the present invention.

FIG. 4 is an embodiment of a processor including multiple cores.

FIG. 5 is a block diagram of a micro-architecture of a processor core inaccordance with one embodiment of the present invention.

FIG. 6 is a block diagram of a micro-architecture of a processor core inaccordance with another embodiment.

FIG. 7 is a block diagram of a micro-architecture of a processor core inaccordance with yet another embodiment.

FIG. 8 is a block diagram of a micro-architecture of a processor core inaccordance with a still further embodiment.

FIG. 9 is a block diagram of a processor in accordance with anotherembodiment of the present invention.

FIG. 10 is a block diagram of a representative SoC in accordance with anembodiment of the present invention.

FIG. 11 is a block diagram of another example SoC in accordance with anembodiment of the present invention.

FIG. 12 is a block diagram of an example system with which embodimentscan be used.

FIG. 13 is a block diagram of another example system with whichembodiments may be used.

FIG. 14 is a block diagram of a representative computer system.

FIG. 15 is a block diagram of a system in accordance with an embodimentof the present invention.

FIG. 16 is a block diagram illustrating an IP core development systemused to manufacture an integrated circuit to perform operationsaccording to an embodiment.

FIG. 17 is a time diagram illustrating processor power control inaccordance with an embodiment of the present invention.

FIG. 18 is a time diagram illustrating processor power control inaccordance with another embodiment of the present invention.

FIG. 19 is a block diagram of a system in accordance with an embodimentof the present invention.

FIG. 20 is a flow diagram of a method in accordance with an embodimentof the present invention.

DETAILED DESCRIPTION

In various embodiments, a processor may provide for improved sustainedperformance when in a constrained environment. More specifically, aprocessor may be controlled to exit an idle state when a workload isexecuted for instance as a response to an interrupt, timer tick (alsointerrupt), or other wake event. In particular the workload may be aresponsiveness workload. As used herein, the term “responsivenessworkload” includes a given process, thread or so forth in whichinteraction with a user of a computing system occurs. A wide variety ofsuch responsiveness workloads are possible; examples includeapplications in which a user interacts with a system via a keyboard,microphone, touchscreen or so forth, applications which require minimumquality of service (e.g., video or audio streaming and editing, inputoutput such as disk drive reads, etc.). In some embodiments,responsiveness workloads may be explicitly marked as such by anoperating system or an application by way of an architectural interfacesuch as a machine specific register (MSR) or memory mapped input output(MMIO). In such embodiments, if the application or the OS schedulermarks an application as responsiveness required, then the operationdescribed herein may proceed.

As described herein, an idle state exit may occur with the processorproceeding directly to a highest or maximum performance state or level.This is the case, since a given budget (e.g., power, thermal or timer)is accumulated while the processor is in the idle state. To enable amore sustained workload duration, the processor may be controlled tooperate at this maximum performance state for a time limited durationand to thereafter automatically proceed to one or more intermediateperformance levels while a relevant budget remains available, until suchbudget is exhausted. Note that with operation at intermediateperformance levels, budget is also saved for additional bursts, shouldworkload increase. After the budget is exhausted, the processor may becontrolled to operate at a sustained performance level. By providingsuch control, improved sustained performance may be achieved byoperating at a performance level that fully utilizes a given budgetthroughout operation of the workload. The idle state can sleep state ora low activity run. In some embodiments, the idle state may be a truelow power or sleep state. In other cases the idle state may be a periodof low active state such as running at low frequency because theapplication does not need more performance and does not need to runfaster.

Since oftentimes it is unknown for how long a responsiveness workloadwill execute (such as where a user is interacting with a computingsystem), embodiments provide for adaptive techniques to enable thissustained operation. As such, embodiments operate to provide consistentresponsive experience while balancing one or more budgets between userperceived responsiveness and longer workloads. As will be describedherein, embodiments implement an attack-sustain-decay technique in whichexecution begins at a high performance state, and then proceeds througha longer, lower performance state and finally to a base levelperformance state. Note that this attack-sustain-decay technique may beanalogized to a musical instrument, such as hitting a piano key, whichbegins with a high-pitched sound followed by a sustained sound until thekey is released.

Although the following embodiments are described with reference toenergy conservation and energy efficiency in specific integratedcircuits, such as in computing platforms or processors, otherembodiments are applicable to other types of integrated circuits andlogic devices. Similar techniques and teachings of embodiments describedherein may be applied to other types of circuits, or semiconductordevices that may also benefit from better energy efficiency and energyconservation. For example, the disclosed embodiments are not limited toany particular type of computer systems. That is, disclosed embodimentscan be used in many different system types, ranging from servercomputers (e.g., tower, rack, blade, micro-server and so forth),communications systems, storage systems, desktop computers of anyconfiguration, laptop, notebook, and tablet computers (including 2:1tablets, phablets and so forth), and may be also used in other devices,such as handheld devices, systems on chip (SoCs), and embeddedapplications. Some examples of handheld devices include cellular phonessuch as smartphones, Internet protocol devices, digital cameras,personal digital assistants (PDAs), and handheld PCs. Embeddedapplications may typically include a microcontroller, a digital signalprocessor (DSP), network computers (NetPC), set-top boxes, network hubs,wide area network (WAN) switches, wearable devices, or any other systemthat can perform the functions and operations taught below. More so,embodiments may be implemented in mobile terminals having standard voicefunctionality such as mobile phones, smartphones and phablets, and/or innon-mobile terminals without a standard wireless voice functioncommunication capability, such as many wearables, tablets, notebooks,desktops, micro-servers, servers and so forth. Moreover, theapparatuses, methods, and systems described herein are not limited tophysical computing devices, but may also relate to softwareoptimizations for energy conservation and efficiency. As will becomereadily apparent in the description below, the embodiments of methods,apparatuses, and systems described herein (whether in reference tohardware, firmware, software, or a combination thereof) are vital to a‘green technology’ future, such as for power conservation and energyefficiency in products that encompass a large portion of the US economy.

Referring now to FIG. 1, shown is a block diagram of a portion of asystem accordance with an embodiment of the present invention. As shownin FIG. 1, system 100 may include various components, including aprocessor 110 which as shown is a multicore processor. Processor 110 maybe coupled to a power supply 150 via an external voltage regulator 160,which may perform a first voltage conversion to provide a primaryregulated voltage Vreg to processor 110.

As seen, processor 110 may be a single die processor including multiplecores 120 a-120 n. In addition, each core may be associated with anintegrated voltage regulator (IVR) 125 a-125 n which receives theprimary regulated voltage and generates an operating voltage to beprovided to one or more agents of the processor associated with the IVR.Accordingly, an IVR implementation may be provided to allow forfine-grained control of voltage and thus power and performance of eachindividual core. As such, each core can operate at an independentvoltage and frequency, enabling great flexibility and affording wideopportunities for balancing power consumption with performance. In someembodiments, the use of multiple IVRs enables the grouping of componentsinto separate power planes, such that power is regulated and supplied bythe IVR to only those components in the group. During power management,a given power plane of one IVR may be powered down or off when theprocessor is placed into a certain low power state, while another powerplane of another IVR remains active, or fully powered. Similarly, cores120 may include or be associated with independent clock generationcircuitry such as one or more phase lock loops (PLCs) to controloperating frequency of each core 120 independently.

Still referring to FIG. 1, additional components may be present withinthe processor including an input/output interface (IF) 132, anotherinterface 134, and an integrated memory controller (IMC) 136. As seen,each of these components may be powered by another integrated voltageregulator 125 _(x). In one embodiment, interface 132 may enableoperation for an Intel® Quick Path Interconnect (QM) interconnect, whichprovides for point-to-point (PtP) links in a cache coherent protocolthat includes multiple layers including a physical layer, a link layerand a protocol layer. In turn, interface 134 may communicate via aPeripheral Component Interconnect Express (PCIe™) protocol.

Also shown is a power control unit (PCU) 138, which may includecircuitry including hardware, software and/or firmware to perform powermanagement operations with regard to processor 110. As seen, PCU 138provides control information to external voltage regulator 160 via adigital interface 162 to cause the voltage regulator to generate theappropriate regulated voltage. PCU 138 also provides control informationto IVRs 125 via another digital interface 163 to control the operatingvoltage generated (or to cause a corresponding IVR to be disabled in alow power mode). In various embodiments, PCU 138 may include a varietyof power management logic units to perform hardware-based powermanagement. Such power management may be wholly processor controlled(e.g., by various processor hardware, and which may be triggered byworkload and/or power, thermal or other processor constraints) and/orthe power management may be performed responsive to external sources(such as a platform or power management source or system software). Asdescribed herein PCU 138 may be configured to cause direct entry into amaximum performance state after a wake up from an idle or other lowpower state, e.g., to handle a responsiveness workload, withcontrollable demotion thereafter to one or more lower performancestates.

In FIG. 1, PCU 138 is illustrated as being present as a separate logicof the processor. In other cases PCU logic 138 may execute on a givenone or more of cores 120. In some cases, PCU 138 may be implemented as amicrocontroller (dedicated or general-purpose) or other control logicconfigured to execute its own dedicated power management code, sometimesreferred to as P-code. In yet other embodiments, power managementoperations to be performed by PCU 138 may be implemented externally to aprocessor, such as by way of a separate power management integratedcircuit (PMIC) or other component external to the processor. In yetother embodiments, power management operations to be performed by PCU138 may be implemented within BIOS or other system software.

Embodiments may be particularly suitable for a multicore processor inwhich each of multiple cores can operate at an independent voltage andfrequency point. As used herein the term “domain” is used to mean acollection of hardware and/or logic that operates at the same voltageand frequency point. In addition, a multicore processor can furtherinclude other non-core processing engines such as fixed function units,graphics engines, and so forth. Such processor can include independentdomains other than the cores, such as one or more domains associatedwith a graphics engine (referred to herein as a graphics domain) and oneor more domains associated with non-core circuitry, referred to hereinas an uncore or a system agent. Although many implementations of amulti-domain processor can be formed on a single semiconductor die,other implementations can be realized by a multi-chip package in whichdifferent domains can be present on different semiconductor die of asingle package.

While not shown for ease of illustration, understand that additionalcomponents may be present within processor 110 such as uncore logic, andother components such as internal memories, e.g., one or more levels ofa cache memory hierarchy and so forth. Furthermore, while shown in theimplementation of FIG. 1 with an integrated voltage regulator,embodiments are not so limited. For example, other regulated voltagesmay be provided to on-chip resources from external voltage regulator 160or one or more additional external sources of regulated voltages.

Note that the power management techniques described herein may beindependent of and complementary to an operating system (OS)-based powermanagement (OSPM) mechanism. According to one example OSPM technique, aprocessor can operate at various performance states or levels, so-calledP-states, namely from P0 to PN. In general, the P1 performance state maycorrespond to the highest guaranteed performance state that can berequested by an OS. In addition to this P1 state, the OS can furtherrequest a higher performance state, namely a P0 state. This P0 state maythus be an opportunistic, overclocking, or turbo mode state in which,when power and/or thermal budget is available, processor hardware canconfigure the processor or at least portions thereof to operate at ahigher than guaranteed frequency. In many implementations a processorcan include multiple so-called bin frequencies above the P1 guaranteedmaximum frequency, exceeding to a maximum peak frequency of theparticular processor, as fused or otherwise written into the processorduring manufacture. In addition, according to one OSPM mechanism, aprocessor can operate at various power states or levels. With regard topower states, an OSPM mechanism may specify different power consumptionstates, generally referred to as C-states, C0, C1 to Cn States. When acore is active, it runs at a C0 state, and when the core is idle it maybe placed in a core low power state, also called a core non-zero C-state(e.g., C1-C6 states), with each C-state being at a lower powerconsumption level (such that C6 is a deeper low power state than C1, andso forth).

Understand that many different types of power management techniques maybe used individually or in combination in different embodiments. Asrepresentative examples, a power controller may control the processor tobe power managed by some form of dynamic voltage frequency scaling(DVFS) in which an operating voltage and/or operating frequency of oneor more cores or other processor logic may be dynamically controlled toreduce power consumption in certain situations. In an example, DVFS maybe performed using Enhanced Intel SpeedStep™ technology available fromIntel Corporation, Santa Clara, Calif., to provide optimal performanceat a lowest power consumption level. In another example, DVFS may beperformed using Intel TurboBoost™ technology to enable one or more coresor other compute engines to operate at a higher than guaranteedoperating frequency based on conditions (e.g., workload andavailability).

Another power management technique that may be used in certain examplesis dynamic swapping of workloads between different compute engines. Forexample, the processor may include asymmetric cores or other processingengines that operate at different power consumption levels, such that ina power constrained situation, one or more workloads can be dynamicallyswitched to execute on a lower power core or other compute engine.Another exemplary power management technique is hardware duty cycling(HDC), which may cause cores and/or other compute engines to beperiodically enabled and disabled according to a duty cycle, such thatone or more cores may be made inactive during an inactive period of theduty cycle and made active during an active period of the duty cycle.

Power management techniques also may be used when constraints exist inan operating environment. For example, when a power and/or thermalconstraint is encountered, power may be reduced by reducing operatingfrequency and/or voltage. Other power management techniques includethrottling instruction execution rate or limiting scheduling ofinstructions. Still further, it is possible for instructions of a giveninstruction set architecture to include express or implicit direction asto power management operations. Although described with these particularexamples, understand that many other power management techniques may beused in particular embodiments.

Embodiments can be implemented in processors for various marketsincluding server processors, desktop processors, mobile processors andso forth. Referring now to FIG. 2, shown is a block diagram of aprocessor in accordance with an embodiment of the present invention. Asshown in FIG. 2, processor 200 may be a multicore processor including aplurality of cores 210 _(a)-210 _(n). In one embodiment, each such coremay be of an independent power domain and can be configured to enter andexit active states and/or maximum performance states based on workload.One or more cores 210 may be heterogeneous to the other cores, e.g.,having different micros architectures, instruction set architectures,pipeline depths, power and performance capabilities. The various coresmay be coupled via an interconnect 215 to a system agent or uncore 220that includes various components. As seen, the uncore 220 may include ashared cache 230 which may be a last level cache. In addition, theuncore may include an integrated memory controller 240 to communicatewith a system memory (not shown in FIG. 2), e.g., via a memory bus.Uncore 220 also includes various interfaces 250 and a power control unit255, which may include logic to perform the power management techniques,including the controllable demotion(s) from a maximum performance stateto a sustained performance state, as described herein.

In addition, by interfaces 250 a-250 n, connection can be made tovarious off-chip components such as peripheral devices, mass storage andso forth. While shown with this particular implementation in theembodiment of FIG. 2, the scope of the present invention is not limitedin this regard.

Referring now to FIG. 3, shown is a block diagram of a multi-domainprocessor in accordance with another embodiment of the presentinvention. As shown in the embodiment of FIG. 3, processor 300 includesmultiple domains. Specifically, a core domain 310 can include aplurality of cores 310 a-310 n, a graphics domain 320 can include one ormore graphics engines, and a system agent domain 350 may further bepresent. In some embodiments, system agent domain 350 may execute at anindependent frequency than the core domain and may remain powered on atall times to handle power control events and power management such thatdomains 310 and 320 can be controlled to dynamically enter into and exithigh power and low power states. Each of domains 310 and 320 may operateat different voltage and/or power. Note that while only shown with threedomains, understand the scope of the present invention is not limited inthis regard and additional domains can be present in other embodiments.For example, multiple core domains may be present each including atleast one core.

In general, each core 310 may further include low level caches inaddition to various execution units and additional processing elements.In turn, the various cores may be coupled to each other and to a sharedcache memory formed of a plurality of units of a last level cache (LLC)340 a-340 n. In various embodiments, LLC 340 may be shared amongst thecores and the graphics engine, as well as various media processingcircuitry. As seen, a ring interconnect 330 thus couples the corestogether, and provides interconnection between the cores, graphicsdomain 320 and system agent circuitry 350. In one embodiment,interconnect 330 can be part of the core domain. However in otherembodiments the ring interconnect can be of its own domain.

As further seen, system agent domain 350 may include display controller352 which may provide control of and an interface to an associateddisplay. As further seen, system agent domain 350 may include a powercontrol unit 355 which can include logic to perform the power managementtechniques described herein.

As further seen in FIG. 3, processor 300 can further include anintegrated memory controller (IMC) 370 that can provide for an interfaceto a system memory, such as a dynamic random access memory (DRAM).Multiple interfaces 380 a-380 n may be present to enable interconnectionbetween the processor and other circuitry. For example, in oneembodiment at least one direct media interface (DMI) interface may beprovided as well as one or more PCIe™ interfaces. Still further, toprovide for communications between other agents such as additionalprocessors or other circuitry, one or more QPI interfaces may also beprovided. Although shown at this high level in the embodiment of FIG. 3,understand the scope of the present invention is not limited in thisregard.

Referring to FIG. 4, an embodiment of a processor including multiplecores is illustrated. Processor 400 includes any processor or processingdevice, such as a microprocessor, an embedded processor, a digitalsignal processor (DSP), a network processor, a handheld processor, anapplication processor, a co-processor, a system on a chip (SoC), orother device to execute code. Processor 400, in one embodiment, includesat least two cores—cores 401 and 402, which may include asymmetric coresor symmetric cores (the illustrated embodiment). However, processor 400may include any number of processing elements that may be symmetric orasymmetric.

In one embodiment, a processing element refers to hardware or logic tosupport a software thread. Examples of hardware processing elementsinclude: a thread unit, a thread slot, a thread, a process unit, acontext, a context unit, a logical processor, a hardware thread, a core,and/or any other element, which is capable of holding a state for aprocessor, such as an execution state or architectural state. In otherwords, a processing element, in one embodiment, refers to any hardwarecapable of being independently associated with code, such as a softwarethread, operating system, application, or other code. A physicalprocessor typically refers to an integrated circuit, which potentiallyincludes any number of other processing elements, such as cores orhardware threads.

A core often refers to logic located on an integrated circuit capable ofmaintaining an independent architectural state, wherein eachindependently maintained architectural state is associated with at leastsome dedicated execution resources. In contrast to cores, a hardwarethread typically refers to any logic located on an integrated circuitcapable of maintaining an independent architectural state, wherein theindependently maintained architectural states share access to executionresources. As can be seen, when certain resources are shared and othersare dedicated to an architectural state, the line between thenomenclature of a hardware thread and core overlaps. Yet often, a coreand a hardware thread are viewed by an operating system as individuallogical processors, where the operating system is able to individuallyschedule operations on each logical processor.

Physical processor 400, as illustrated in FIG. 4, includes two cores,cores 401 and 402. Here, cores 401 and 402 are considered symmetriccores, i.e., cores with the same configurations, functional units,and/or logic. In another embodiment, core 401 includes an out-of-orderprocessor core, while core 402 includes an in-order processor core.However, cores 401 and 402 may be individually selected from any type ofcore, such as a native core, a software managed core, a core adapted toexecute a native instruction set architecture (ISA), a core adapted toexecute a translated ISA, a co-designed core, or other known core. Yetto further the discussion, the functional units illustrated in core 401are described in further detail below, as the units in core 402 operatein a similar manner.

As depicted, core 401 includes two hardware threads 401 a and 401 b,which may also be referred to as hardware thread slots 401 a and 401 b.Therefore, software entities, such as an operating system, in oneembodiment potentially view processor 400 as four separate processors,i.e., four logical processors or processing elements capable ofexecuting four software threads concurrently. As alluded to above, afirst thread is associated with architecture state registers 401 a, asecond thread is associated with architecture state registers 401 b, athird thread may be associated with architecture state registers 402 a,and a fourth thread may be associated with architecture state registers402 b. Here, each of the architecture state registers (401 a, 401 b, 402a, and 402 b) may be referred to as processing elements, thread slots,or thread units, as described above. As illustrated, architecture stateregisters 401 a are replicated in architecture state registers 401 b, soindividual architecture states/contexts are capable of being stored forlogical processor 401 a and logical processor 401 b. In core 401, othersmaller resources, such as instruction pointers and renaming logic inallocator and renamer block 430 may also be replicated for threads 401 aand 401 b. Some resources, such as re-order buffers inreorder/retirement unit 435, branch target buffer and instructiontranslation lookaside buffer (BTB and I-TLB) 420, load/store buffers,and queues may be shared through partitioning. Other resources, such asgeneral purpose internal registers, page-table base register(s),low-level data-cache and data-TLB 450, execution unit(s) 440, andportions of out-of-order unit 435 are potentially fully shared.

Processor 400 often includes other resources, which may be fully shared,shared through partitioning, or dedicated by/to processing elements. InFIG. 4, an embodiment of a purely exemplary processor with illustrativelogical units/resources of a processor is illustrated. Note that aprocessor may include, or omit, any of these functional units, as wellas include any other known functional units, logic, or firmware notdepicted. As illustrated, core 401 includes a simplified, representativeout-of-order (OOO) processor core. But an in-order processor may beutilized in different embodiments. The OOO core includes a branch targetbuffer 420 to predict branches to be executed/taken and aninstruction-translation buffer (I-TLB) 420 to store address translationentries for instructions.

Core 401 further includes decode module 425 coupled to a fetch unit todecode fetched elements. Fetch logic, in one embodiment, includesindividual sequencers associated with thread slots 401 a, 401 b,respectively. Usually core 401 is associated with a first ISA, whichdefines/specifies instructions executable on processor 400. Oftenmachine code instructions that are part of the first ISA include aportion of the instruction (referred to as an opcode), whichreferences/specifies an instruction or operation to be performed. Decodelogic 425 includes circuitry that recognizes these instructions fromtheir opcodes and passes the decoded instructions on in the pipeline forprocessing as defined by the first ISA. For example, decoders 425, inone embodiment, include logic designed or adapted to recognize specificinstructions, such as transactional instruction. As a result of therecognition by decoders 425, the architecture or core 401 takesspecific, predefined actions to perform tasks associated with theappropriate instruction. It is important to note that any of the tasks,blocks, operations, and methods described herein may be performed inresponse to a single or multiple instructions; some of which may be newor old instructions.

In one example, allocator and renamer block 430 includes an allocator toreserve resources, such as register files to store instructionprocessing results. However, threads 401 a and 401 b are potentiallycapable of out-of-order execution, where allocator and renamer block 430also reserves other resources, such as reorder buffers to trackinstruction results. Unit 430 may also include a register renamer torename program/instruction reference registers to other registersinternal to processor 400. Reorder/retirement unit 435 includescomponents, such as the reorder buffers mentioned above, load buffers,and store buffers, to support out-of-order execution and later in-orderretirement of instructions executed out-of-order.

Scheduler and execution unit(s) block 440, in one embodiment, includes ascheduler unit to schedule instructions/operation on execution units.For example, a floating point instruction is scheduled on a port of anexecution unit that has an available floating point execution unit.Register files associated with the execution units are also included tostore information instruction processing results. Exemplary executionunits include a floating point execution unit, an integer executionunit, a jump execution unit, a load execution unit, a store executionunit, and other known execution units.

Lower level data cache and data translation lookaside buffer (D-TLB) 450are coupled to execution unit(s) 440. The data cache is to storerecently used/operated on elements, such as data operands, which arepotentially held in memory coherency states. The D-TLB is to storerecent virtual/linear to physical address translations. As a specificexample, a processor may include a page table structure to breakphysical memory into a plurality of virtual pages.

Here, cores 401 and 402 share access to higher-level or further-outcache 410, which is to cache recently fetched elements. Note thathigher-level or further-out refers to cache levels increasing or gettingfurther away from the execution unit(s). In one embodiment, higher-levelcache 410 is a last-level data cache—last cache in the memory hierarchyon processor 400—such as a second or third level data cache. However,higher level cache 410 is not so limited, as it may be associated withor includes an instruction cache. A trace cache—a type of instructioncache—instead may be coupled after decoder 425 to store recently decodedtraces.

In the depicted configuration, processor 400 also includes bus interfacemodule 405 and a power control unit 460, which may perform powermanagement in accordance with an embodiment of the present invention. Inthis scenario, bus interface 405 is to communicate with devices externalto processor 400, such as system memory and other components.

A memory controller 470 may interface with other devices such as one ormany memories. In an example, bus interface 405 includes a ringinterconnect with a memory controller for interfacing with a memory anda graphics controller for interfacing with a graphics processor. In anSoC environment, even more devices, such as a network interface,coprocessors, memory, graphics processor, and any other known computerdevices/interface may be integrated on a single die or integratedcircuit to provide small form factor with high functionality and lowpower consumption.

Referring now to FIG. 5, shown is a block diagram of amicro-architecture of a processor core in accordance with one embodimentof the present invention. As shown in FIG. 5, processor core 500 may bea multi-stage pipelined out-of-order processor. Core 500 may operate atvarious voltages based on a received operating voltage, which may bereceived from an integrated voltage regulator or external voltageregulator.

As seen in FIG. 5, core 500 includes front end units 510, which may beused to fetch instructions to be executed and prepare them for use laterin the processor pipeline. For example, front end units 510 may includea fetch unit 501, an instruction cache 503, and an instruction decoder505. In some implementations, front end units 510 may further include atrace cache, along with microcode storage as well as a micro-operationstorage. Fetch unit 501 may fetch macro-instructions, e.g., from memoryor instruction cache 503, and feed them to instruction decoder 505 todecode them into primitives, i.e., micro-operations for execution by theprocessor.

Coupled between front end units 510 and execution units 520 is anout-of-order (OOO) engine 515 that may be used to receive themicro-instructions and prepare them for execution. More specifically OOOengine 515 may include various buffers to re-order micro-instructionflow and allocate various resources needed for execution, as well as toprovide renaming of logical registers onto storage locations withinvarious register files such as register file 530 and extended registerfile 535. Register file 530 may include separate register files forinteger and floating point operations. For purposes of configuration,control, and additional operations, a set of machine specific registers(MSRs) 538 may also be present and accessible to various logic withincore 500 (and external to the core).

Various resources may be present in execution units 520, including, forexample, various integer, floating point, and single instructionmultiple data (SIMD) logic units, among other specialized hardware. Forexample, such execution units may include one or more arithmetic logicunits (ALUs) 522 and one or more vector execution units 524, among othersuch execution units.

Results from the execution units may be provided to retirement logic,namely a reorder buffer (ROB) 540. More specifically, ROB 540 mayinclude various arrays and logic to receive information associated withinstructions that are executed. This information is then examined by ROB540 to determine whether the instructions can be validly retired andresult data committed to the architectural state of the processor, orwhether one or more exceptions occurred that prevent a proper retirementof the instructions. Of course, ROB 540 may handle other operationsassociated with retirement.

As shown in FIG. 5, ROB 540 is coupled to a cache 550 which, in oneembodiment may be a low level cache (e.g., an L1 cache) although thescope of the present invention is not limited in this regard. Also,execution units 520 can be directly coupled to cache 550. From cache550, data communication may occur with higher level caches, systemmemory and so forth. While shown with this high level in the embodimentof FIG. 5, understand the scope of the present invention is not limitedin this regard. For example, while the implementation of FIG. 5 is withregard to an out-of-order machine such as of an Intel® x86 instructionset architecture (ISA), the scope of the present invention is notlimited in this regard. That is, other embodiments may be implemented inan in-order processor, a reduced instruction set computing (RISC)processor such as an ARM-based processor, or a processor of another typeof ISA that can emulate instructions and operations of a different ISAvia an emulation engine and associated logic circuitry.

Referring now to FIG. 6, shown is a block diagram of amicro-architecture of a processor core in accordance with anotherembodiment. In the embodiment of FIG. 6, core 600 may be a low powercore of a different micro-architecture, such as an Intel® Atom™-basedprocessor having a relatively limited pipeline depth designed to reducepower consumption. As seen, core 600 includes an instruction cache 610coupled to provide instructions to an instruction decoder 615. A branchpredictor 605 may be coupled to instruction cache 610. Note thatinstruction cache 610 may further be coupled to another level of a cachememory, such as an L2 cache (not shown for ease of illustration in FIG.6). In turn, instruction decoder 615 provides decoded instructions to anissue queue (IQ) 620 for storage and delivery to a given executionpipeline. A microcode ROM 618 is coupled to instruction decoder 615.

A floating point pipeline 630 includes a floating point (FP) registerfile 632 which may include a plurality of architectural registers of agiven bit width such as 128, 256 or 512 bits. Pipeline 630 includes afloating point scheduler 634 to schedule instructions for execution onone of multiple execution units of the pipeline. In the embodimentshown, such execution units include an ALU 635, a shuffle unit 636, anda floating point adder 638. In turn, results generated in theseexecution units may be provided back to buffers and/or registers ofregister file 632. Of course understand while shown with these fewexample execution units, additional or different floating pointexecution units may be present in another embodiment.

An integer pipeline 640 also may be provided. In the embodiment shown,pipeline 640 includes an integer (INT) register file 642 which mayinclude a plurality of architectural registers of a given hit width suchas 128 or 256 bits. Pipeline 640 includes an integer execution (IE)scheduler 644 to schedule instructions for execution on one of multipleexecution units of the pipeline. In the embodiment shown, such executionunits include an ALU 645, a shifter unit 646, and a jump execution unit(JEU) 648. In turn, results generated in these execution units may beprovided back to buffers and/or registers of register file 642. Ofcourse understand while shown with these few example execution units,additional or different integer execution units may be present inanother embodiment.

A memory execution (ME) scheduler 650 may schedule memory operations forexecution in an address generation unit (AGU) 652, which is also coupledto a TLB 654. As seen, these structures may couple to a data cache 660,which may be a L0 and/or L1 data cache that in turn couples toadditional levels of a cache memory hierarchy, including an L2 cachememory.

To provide support for out-of-order execution, an allocator/renamer 670may be provided, in addition to a reorder buffer 680, which isconfigured to reorder instructions executed out of order for retirementin order. Although shown with this particular pipeline architecture inthe illustration of FIG. 6, understand that many variations andalternatives are possible.

Note that in a processor having asymmetric cores, such as in accordancewith the micro-architectures of FIGS. 5 and 6, workloads may bedynamically swapped between the cores for power management reasons, asthese cores, although having different pipeline designs and depths, maybe of the same or related ISA. Such dynamic core swapping may beperformed in a manner transparent to a user application (and possiblykernel also).

Referring to FIG. 7, shown is a block diagram of a micro-architecture ofa processor core in accordance with yet another embodiment. Asillustrated in FIG. 7, a core 700 may include a multi-staged in-orderpipeline to execute at very low power consumption levels. As one suchexample, processor 700 may have a micro-architecture in accordance withan ARM Cortex A53 design available from ARM Holdings, LTD., Sunnyvale,Calif. In an implementation, an 8-stage pipeline may be provided that isconfigured to execute both 32-bit and 64-bit code. Core 700 includes afetch unit 710 that is configured to fetch instructions and provide themto a decode unit 715, which may decode the instructions, e.g.,macro-instructions of a given ISA such as an ARMv8 ISA. Note furtherthat a queue 730 may couple to decode unit 715 to store decodedinstructions. Decoded instructions are provided to an issue logic 725,where the decoded instructions may be issued to a given one of multipleexecution units.

With further reference to FIG. 7, issue logic 725 may issue instructionsto one of multiple execution units. In the embodiment shown, theseexecution units include an integer unit 735, a multiply unit 740, afloating point/vector unit 750, a dual issue unit 760, and a load/storeunit 770. The results of these different execution units may be providedto a writeback (WB) unit 780. Understand that while a single writebackunit is shown for ease of illustration, in some implementations separatewriteback units may be associated with each of the execution units.Furthermore, understand that while each of the units and logic shown inFIG. 7 is represented at a high level, a particular implementation mayinclude more or different structures. A processor designed using one ormore cores having a pipeline as in FIG. 7 may be implemented in manyharem end products, extending from mobile devices to server systems.

Referring to FIG. 8, shown is a block diagram of a micro-architecture ofa processor core in accordance with a still further embodiment. Asillustrated in FIG. 8, a core 800 may include a multi-stage multi-issueout-of-order pipeline to execute at very high performance levels (whichmay occur at higher power consumption levels than core 700 of FIG. 7).As one such example, processor 800 may have a microarchitecture inaccordance with an ARM Cortex A57 design. In an implementation, a 15 (orgreater)-stage pipeline may be provided that is configured to executeboth 32-bit and 64-bit code. In addition, the pipeline may provide for 3(or greater)-wide and 3 (or greater)-issue operation. Core 800 includesa fetch unit 810 that is configured to fetch instructions and providethem to a decoder/renamer/dispatcher unit 815 coupled to a cache 820.Unit 815 may decode the instructions, e.g., macro-instructions of anARMv8 instruction set architecture, rename register references withinthe instructions, and dispatch the instructions (eventually) to aselected execution unit. Decoded instructions may be stored in a queue825. Note that while a single queue structure is shown for ease ofillustration in FIG. 8, understand that separate queues may be providedfor each of the multiple different types of execution units.

Also shown in FIG. 8 is an issue logic 830 from which decodedinstructions stored in queue 825 may be issued to a selected executionunit. Issue logic 830 also may be implemented in a particular embodimentwith a separate issue logic for each of the multiple different types ofexecution units to which issue logic 830 couples.

Decoded instructions may be issued to a given one of multiple executionunits. In the embodiment shown, these execution units include one ormore integer units 835, a multiply unit 840, a floating point/vectorunit 850, a branch unit 860, and a load/store unit 870. In anembodiment, floating point/vector unit 850 may be configured to handleSIMD or vector data of 128 or 256 bits. Still further, floatingpoint/vector execution Unit 850 may perform IEEE-754 double precisionfloating-point operations. The results of these different executionunits may be provided to a writeback unit 880. Note that in someimplementations separate writeback units may be associated with each ofthe execution units. Furthermore, understand that while each of theunits and logic shown in FIG. 8 is represented at a high level, aparticular implementation may include more or different structures.

Note that in a processor having asymmetric cores, such as in accordancewith the micro-architectures of FIGS. 7 and 8, workloads may bedynamically swapped for power management reasons, as these cores,although having different pipeline designs and depths, may be of thesame or related ISA. Such dynamic core swapping may be performed in amanner transparent to a user application (and possibly kernel also).

A processor designed using one or more cores having pipelines as in anyone or more of FIGS. 5-8 may be implemented in many different endproducts, extending from mobile devices to server systems. Referring nowto FIG. 9, shown is a block diagram of a processor in accordance withanother embodiment of the present invention. In the embodiment of FIG.9, processor 900 may be a SoC including multiple domains, each of whichmay be controlled to operate at an independent operating voltage andoperating frequency. As a specific illustrative example, processor 900may be an Intel® Architecture Core™-based processor such as an i3, i5,i7 or another such processor available from Intel Corporation. However,other low power processors such as available from Advanced MicroDevices, Inc. (AMD) of Sunnyvale, Calif., an ARM-based design from ARMHoldings, Ltd. or licensee thereof or a MIPS-based design from MIPSTechnologies, Inc. of Sunnyvale, Calif., or their licensees or adoptersmay instead be present in other embodiments such as an Apple A7processor, a Qualcomm Snapdragon processor, or Texas Instruments OMAPprocessor. Such SoC may be used in a low power system such as asmartphone, tablet computer, phablet computer, Ultrabook™ computer orother portable computing device, which may incorporate a heterogeneoussystem architecture having a heterogeneous system architecture-basedprocessor design.

In the high level view shown in FIG. 9, processor 900 includes aplurality of core units 910 a-910 n. Each core unit may include one ormore processor cores, one or more cache memories and other circuitry.Each core unit 910 may support one or more instruction sets (e.g., anx86 instruction set (with some extensions that have been added withnewer versions); a MIPS instruction set; an ARM instruction set (withoptional additional extensions such as NEON)) or other instruction setor combinations thereof. Note that some of the core units may beheterogeneous resources (e.g., of a different design). In addition, eachsuch core may be coupled to a cache memory (not shown) which in anembodiment may be a shared level two (L2) cache memory. A non-volatilestorage 930 may be used to store various program and other data. Forexample, this storage may be used to store at least portions ofmicrocode, boot information such as a BIOS, other system software or soforth.

Each core unit 910 may also include an interface such as a bus interfaceunit to enable interconnection to additional circuitry of the processor.In an embodiment, each core unit 910 couples to a coherent fabric thatmay act as a primary cache coherent on-die interconnect that in turncouples to a memory controller 935. In turn, memory controller 935controls communications with a memory such as a DRAM (not shown for easeof illustration in FIG. 9).

In addition to core units, additional processing engines are presentwithin the processor, including at least one graphics unit 920 which mayinclude one or more graphics processing units (GPUs) to perform graphicsprocessing as well as to possibly execute general purpose operations onthe graphics processor (so-called GPGPU operation). In addition, atleast one image signal processor 925 may be present. Signal processor925 may be configured to process incoming image data received from oneor more capture devices, either internal to the SoC or off-chip.

Other accelerators also may be present. In the illustration of FIG. 9, avideo coder 950 may perform coding operations including encoding anddecoding for video information, e.g., providing hardware accelerationsupport for high definition video content. A display controller 955further may be provided to accelerate display operations includingproviding support for internal and external displays of a system. Inaddition, a security processor 945 may be present to perform securityoperations such as secure boot operations, various cryptographyoperations and so forth.

Each of the units may have its power consumption controlled via a powermanager 940, which may include control logic to perform the variouspower management techniques, including the controllable demotion(s) frommaximum performance state to sustained performance state, as describedherein.

In some embodiments, SoC 900 may further include a non-coherent fabriccoupled to the coherent fabric to which various peripheral devices maycouple. One or more interfaces 960 a-960 d enable communication with oneor more off-chip devices. Such communications may be via a variety ofcommunication protocols such as PCIe™, GPIO, USB, I²C, UART, MIPI, SDIO,DDR, SPI, HDMI, among other types of communication protocols. Althoughshown at this high level in the embodiment of FIG. 9, understand thescope of the present invention is not limited in this regard.

Referring now to FIG. 10, shown is a block diagram of a representativeSoC. In the embodiment shown, SoC 1000 may be a multi-core SoCconfigured for low power operation to be optimized for incorporationinto a smartphone or other low power device such as a tablet computer orother portable computing device. As an example, SoC 1000 may beimplemented using asymmetric or different types of cores, such ascombinations of higher power and/or low power cores, e.g., out-of-ordercores and in-order cores. In different embodiments, these cores may bebased on an Intel® Architecture™ core design or an ARM architecturedesign. In yet other embodiments, a mix of Intel and ARM cores may beimplemented in a given SoC.

As seen in FIG. 10, SoC 1000 includes a first core domain 1010 having aplurality of first cores 1012 a-1012 d. In an example, these cores maybe low power cores such as in-order cores. In one embodiment these firstcores may be implemented as ARM Cortex A53 cores. In turn, these corescouple to a cache memory 1015 of core domain 1010. In addition, SoC 1000includes a second core domain 1020. In the illustration of FIG. 10,second core domain 1020 has a plurality of second cores 1022 a-1022 d.In an example, these cores may be higher power-consuming cores thanfirst cores 1012. In an embodiment, the second cores may be out-of-ordercores, which may be implemented as ARM Cortex A57 cores. In turn, thesecores couple to a cache memory 1025 of core domain 1020. Note that whilethe example shown in FIG. 10 includes 4 cores in each domain, understandthat more or fewer cores may be present in a given domain in otherexamples.

With further reference to FIG. 10, a graphics domain 1030 also isprovided, which may include one or more graphics processing units (GPUs)configured to independently execute graphics workloads, e.g., providedby one or more cores of core domains 1010 and 1020. As an example, GPUdomain 1030 may be used to provide display support for a variety ofscreen sizes, in addition to providing graphics and display renderingoperations.

As seen, the various domains couple to a coherent interconnect 1040,which in an embodiment may be a cache coherent interconnect fabric thatin turn couples to an integrated memory controller 1050. Coherentinterconnect 1040 may include a shared cache memory, such as an L3cache, in some examples. In an embodiment, memory controller 1050 may bea direct memory controller to provide for multiple channels ofcommunication with an off-chip memory, such as multiple channels of aDRAM (not shown for ease of illustration in FIG. 10).

In different examples, the number of the core domains may vary. Forexample, for a low power SoC suitable for incorporation into a mobilecomputing device, a limited number of core domains such as shown in FIG.10 may be present. Still further, in such low power SoCs, core domain1020 including higher power cores may have fewer numbers of such cores.For example, in one implementation two cores 1022 may be provided toenable operation at reduced power consumption levels. In addition, thedifferent core domains may also be coupled to an interrupt controller toenable dynamic swapping of workloads between the different domains.

In yet other embodiments, a greater number of core domains, as well asadditional optional IP logic may be present, in that an SoC can bescaled to higher performance (and power) levels for incorporation intoother computing devices, such as desktops, servers, high performancecomputing systems, base stations forth. As one such example, 4 coredomains each having a given number of out-of-order cores may beprovided. Still further, in addition to optional GPU support (which asan example may take the form of a GPGPU), one or more accelerators toprovide optimized hardware support for particular functions (e.g. webserving, network processing, switching or so forth) also may beprovided. In addition, an input/output interface may be present tocouple such accelerators to off-chip components.

Referring now to FIG. 11, shown is a block diagram of another exampleSoC. In the embodiment of FIG. 11, SoC 1100 may include variouscircuitry to enable high performance for multimedia applications,communications and other functions. As such, SoC 1100 is suitable forincorporation into a wide variety of portable and other devices, such assmartphones, tablet computers, smart TVs and so forth. In the exampleshown, SoC 1100 includes a central processor unit (CPU) domain 1110. Inan embodiment, a plurality of individual processor cores may be presentin CPU domain 1110. As one example, CPU domain 1110 may be a quad coreprocessor having 4 multithreaded cores. Such processors may behomogeneous or heterogeneous processors, e.g., a mix of low power andhigh power processor cores.

In turn, a GPU domain 1120 is provided to perform advanced graphicsprocessing in one or more GPUs to handle graphics and compute APIs. ADSP unit 1130 may provide one or more low power DSPs for handlinglow-power multimedia applications such as music playback, audio/videoand so forth, in addition to advanced calculations that may occur duringexecution of multimedia instructions. In turn, a communication unit 1140may include various components to provide connectivity via variouswireless protocols, such as cellular communications (including 3G/4GLTE), wireless local area protocols such as Bluetooth™, IEEE 802.11, andso forth.

Still further, a multimedia processor 1150 may be used to performcapture and playback of high definition video and audio content,including processing of user gestures. A sensor unit 1160 may include aplurality of sensors and/or a sensor controller to interface to variousoff-chip sensors present in a given platform. An image signal processor1170 may be provided with one or more separate ISPs to perform imageprocessing with regard to captured content from one or more cameras of aplatform, including still and video cameras.

A display processor 1180 may provide support for connection to a highdefinition display of a given pixel density, including the ability towirelessly communicate content for playback on such display. Stillfurther, a location unit 1190 may include a UPS receiver with supportfor multiple UPS constellations to provide applications highly accuratepositioning information obtained using as such UPS receiver. Understandthat while shown with this particular set of components in the exampleof FIG. 11, many variations and alternatives are possible.

Referring now to FIG. 12, shown is a block diagram of an example systemwith which embodiments can be used. As seen, system 1200 may be asmartphone or other wireless communicator. A baseband processor 1205 isconfigured to perform various signal processing with regard tocommunication signals to be transmitted from or received by the system.In turn, baseband processor 1205 is coupled to an application processor1210, which may be a main CPU of the system to execute an OS and othersystem software, in addition to user applications such as manywell-known social media and multimedia apps. Application processor 1210may further be configured to perform a variety of other computingoperations for the device.

In turn, application processor 1210 can couple to a userinterface/display 1220, e.g., a touch screen display. In addition,application processor 1210 may couple to a memory system including anon-volatile memory, namely a flash memory 1230 and a system memory,namely a dynamic random access memory (DRAM) 1235. As further seen,application processor 1210 further couples to a capture device 1240 suchas one or more image capture devices that can record video and/or stillimages.

Still referring to FIG. 12, a universal integrated circuit card (UICC)1240 comprising a subscriber identity module and possibly a securestorage and cryptoprocessor is also coupled to application processor1210. System 1200 may further include a security processor 1250 that maycouple to application processor 1210. A plurality of sensors 1225 maycouple to application processor 1210 to enable input of a variety ofsensed information such as accelerometer and other environmentalinformation. An audio output device 1295 may provide an interface tooutput sound, e.g., in the form of voice communications, played orstreaming audio data and so forth.

As further illustrated, a near field communication (NFC) contactlessinterface 1260 is provided that communicates in a NFC near field via anNFC antenna 1265. While separate antennae are shown in FIG. 12,understand that in some implementations one antenna or a different setof antennae may be provided to enable various wireless functionality.

A power management integrated circuit (PMIC) 1215 couples to applicationprocessor 1210 to perform platform level power management. To this end,PMIC 1215 may issue power management requests to application processor1210 to enter certain low power states as desired. Furthermore, based onplatform constraints, PMIC 1215 may also control the power level ofother components of system 1200.

To enable communications to be transmitted and received, variouscircuitry may be coupled between baseband processor 1205 and an antenna1290. Specifically, a radio frequency (RF) transceiver 1270 and awireless local area network (WLAN) transceiver 1275 may be present. Ingeneral, RF transceiver 1270 may be used to receive and transmitwireless data and calls according to a given wireless communicationprotocol such as 3G or 4G wireless communication protocol such as inaccordance with a code division multiple access (CDMA), global systemfor mobile communication (GSM), long term evolution (LTE) or otherprotocol. In addition a UPS sensor 1280 may be present. Other wirelesscommunications such as receipt or transmission of radio signals, e.g.,AM/FM and other signals may also be provided. In addition, via WLANtransceiver 1275, local wireless communications can also be realized.

Referring now to FIG. 13, shown is a block diagram of another examplesystem with which embodiments may be used. In the illustration of FIG.13, system 1300 may be mobile low-power system such as a tabletcomputer, 2:1 tablet, phablet or other convertible or standalone tabletsystem. As illustrated, a SoC 1310 is present and may be configured tooperate as an application processor for the device.

A variety of devices may couple to SoC 1310. In the illustration shown,a memory subsystem includes a flash memory 1340 and a DRAM 1345 coupledto SoC 1310. In addition, a touch panel 1320 is coupled to the SoC 1310to provide display capability and user input via touch, includingprovision of a virtual keyboard on a display of touch panel 1320. Toprovide wired network connectivity, SoC 1310 couples to an Ethernetinterface 1330. A peripheral hub 1325 is coupled to SoC 1310 to enableinterfacing with various peripheral devices, such as may be coupled tosystem 1300 by any of various ports or other connectors.

In addition to internal power management circuitry and functionalitywithin SoC 1310, a PMIC 1380 is coupled to SoC 1310 to provideplatform-based power management, e.g., based on whether the system ispowered by a battery 1390 or AC power via an AC adapter 1395. Inaddition to this power source-based power management, PMIC 1380 mayfurther perform platform power management activities based onenvironmental and usage conditions. Still further, PMIC 1380 maycommunicate control and status information to SoC 1310 to cause variouspower management actions within SoC 1310.

Still referring to FIG. 13, to provide for wireless capabilities, a WLANunit 1350 is coupled to SoC 1310 and in turn to an antenna 1355. Invarious implementations, WLAN unit 1350 may provide for communicationaccording to one or more wireless protocols.

As further illustrated, a plurality of sensors 1360 may couple to SoC1310. These sensors may include various accelerometer, environmental andother sensors, including user gesture sensors. Finally, an audio codec1365 is coupled to SoC 1310 to provide an interface to an audio outputdevice 1370. Of course understand that while shown with this particularimplementation in FIG. 13, many variations and alternatives arepossible.

Referring now to FIG. 14, shown is a block diagram of a representativecomputer system such as notebook, Ultrabook™ or other small form factorsystem. A processor 1410, in one embodiment, includes a microprocessor,multi-core processor, multithreaded processor, an ultra low voltageprocessor, an embedded processor, or other known processing element. Inthe illustrated implementation, processor 1410 acts as a main processingunit and central hub for communication with many of the variouscomponents of the system 1400, and may include power managementcircuitry as described herein. As one example, processor 1410 isimplemented as a SoC.

Processor 1410, in one embodiment, communicates with a system memory1415. As an illustrative example, the system memory 1415 is implementedvia multiple memory devices or modules to provide for a given amount ofsystem memory.

To provide for persistent storage of information such as data,applications, one or more operating systems and so forth, a mass storage1420 may also couple to processor 1410. In various embodiments, toenable a thinner and lighter system design as well as to improve systemresponsiveness, this mass storage may be implemented via a SSD or themass storage may primarily be implemented using a hard disk drive (HDD)with a smaller amount of SSD storage to act as a SSD cache to enablenon-volatile storage of context state and other such information duringpower down events so that a fast power up can occur on re-initiation ofsystem activities. Also shown in FIG. 14, a flash device 1422 may becoupled to processor 1410, e.g., via a serial peripheral interface(SPI). This flash device may provide for non-volatile storage of systemsoftware, including a basic input/output software (BIOS) as well asother firmware of the system.

Various input/output (I/O) devices may be present within system 1400.Specifically shown in the embodiment of FIG. 14 is a display 1424 whichmay be a high definition LCD or LED panel that further provides for atouch screen 1425. In one embodiment, display 1424 may be coupled toprocessor 1410 via a display interconnect that can be implemented as ahigh performance graphics interconnect. Touch screen 1425 may be coupledto processor 1410 via another interconnect, which in an embodiment canbe an I²C interconnect. As further shown in FIG. 14, in addition totouch screen 1425, user input by way of touch can also occur via a touchpad 1430 which may be configured within the chassis and may also becoupled to the same I²C interconnect as touch screen 1425.

For perceptual computing and other purposes, various sensors may bepresent within the system and may be coupled to processor 1410 indifferent manners. Certain inertial and environmental sensors may coupleto processor 1410 through a sensor hub 1440, e.g., via an I²Cinterconnect. In the embodiment shown in FIG. 14, these sensors mayinclude an accelerometer 1441, an ambient light sensor (ALS) 1442, acompass 1443 and a gyroscope 1444. Other environmental sensors mayinclude one or more thermal sensors 1446 which in some embodimentscouple to processor 1410 via a system management bus (SMBus) bus.

Also seen in FIG. 14, various peripheral devices may couple to processor1410 via a low pin count (LPC) interconnect. In the embodiment shown,various components can be coupled through an embedded controller 1435.Such components can include a keyboard 1436 (e.g., coupled via a PS2interface), a fan 1437, and a thermal sensor 1439. In some embodiments,touch pad 1430 may also couple to EC 1435 via a PS2 interface. Inaddition, a security processor such as a trusted platform module (TPM)1438 may also couple to processor 1410 via this LPC interconnect.

System 1400 can communicate with external devices in a variety ofmanners, including wirelessly. In the embodiment shown in FIG. 14,various wireless modules, each of which can correspond to a radioconfigured for a particular wireless communication protocol, arepresent. One manner for wireless communication in a short range such asa near field may be via a NFC unit 1445 which may communicate, in oneembodiment with processor 1410 via an SMBus. Note that via this NFC unit1445, devices in close proximity to each other can communicate.

As further seen in FIG. 14, additional wireless units can include othershort range wireless engines including a WLAN unit 1450 and a Bluetooth™unit 1452. Using WLAN unit 1450, Wi-Fi™ communications can be realized,while via Bluetooth™ unit 1452, short range Bluetooth™ communicationscan occur. These units may communicate with processor 1410 Via a givenlink.

In addition, wireless wide area communications, e.g., according to acellular or other wireless wide area protocol, can occur via a WWAN unit1456 which in turn may couple to a subscriber identity module (SIM)1457. In addition, to enable receipt and use of location information, aGPS module 1455 may also be present. Note that in the embodiment shownin FIG. 14, WWAN unit 1456 and an integrated capture device such as acamera module 1454 may communicate via a given link.

To provide for audio inputs and outputs, an audio processor can beimplemented via a digital signal processor (DSP) 1460, which may coupleto processor 1410 via a high definition audio (HDA) link. Similarly, DSP1460 may communicate with an integrated coder/decoder (CODEC) andamplifier 1462 that in turn may couple to output speakers 1463 which maybe implemented within the chassis. Similarly, amplifier and CODEC 1462can be coupled to receive audio inputs from a microphone 1465 which inan embodiment can be implemented via dual array microphones (such as adigital microphone array) to provide for high quality audio inputs toenable voice-activated control of various operations within the system.Note also that audio outputs can be provided from amplifier/CODEC 1462to a headphone jack 1464. Although shown with these particularcomponents in the embodiment of FIG. 14, understand the scope of thepresent invention is not limited in this regard.

Embodiments may be implemented in many different system types. Referringnow to FIG. 15, shown is a block diagram of a system in accordance withan embodiment of the present invention. As shown in FIG. 15,multiprocessor system 1500 is a point-to-point interconnect system, andincludes a first processor 1570 and a second processor 1580 coupled viaa point-to-point interconnect 1550. As shown in FIG. 15, each ofprocessors 1570 and 1580 may be multicore, processors, including firstand second processor cores (i.e., processor cores 1574 a and 1574 b andprocessor cores 1584 a and 1584 b), although potentially many more coresmay be present in the processors. Each of the processors can include aPCU or other power management logic to perform processor-based powermanagement, including autonomously controlled demotion(s) from a maximumperformance state (entered directly after exit from an idle or low powerstate) to a sustained performance state (potentially via one or moreintermediate performance states), as described herein.

Still referring to FIG. 15, first processor 1570 further includes amemory controller hub (MCH) 1572 and point-to-point (P-P) interfaces1576 and 1578. Similarly, second processor 1580 includes a MCH 1582 andP-P interfaces 1586 and 1588. As shown in FIG. 15. MCH's 1572 and 1582couple the processors to respective memories, namely a memory 1532 and amemory 1534, which may be portions of system memory (e.g., DRAM) locallyattached to the respective processors. First processor 1570 and secondprocessor 1580 may be coupled to a chipset 1590 via P-P interconnects1562 and 1564, respectively. As shown in FIG. 15, chipset 1590 includesP-P interfaces 1594 and 1598.

Furthermore, chipset 1590 includes an interface 1592 to couple chipset1590 with a high performance graphics engine 1538, by a P-P interconnect1539. In turn, chipset 1590 may be coupled to a first bus 1516 via aninterface 1596. As shown in FIG. 15, various input/output (I/O) devices1514 may be coupled to first bus 1516, along with a bus bridge 1518which couples first bus 1516 to a second bus 1520. Various devices maybe coupled to second bus 1520 including, for example, a keyboard/mouse1522, communication devices 1526 and a data storage unit 1528 such as adisk drive or other mass storage device which may include code 1530, inone embodiment. Further, an audio I/O 1524 may be coupled to second bus1520. Embodiments can be incorporated into other types of systemsincluding mobile devices such as a smart cellular telephone, tabletcomputer, netbook, Ultrabook™, or so forth.

One or more aspects of at least one embodiment may be implemented byrepresentative code stored on a machine-readable medium which representsand/or defines logic within an integrated circuit such as a processor.For example, the machine-readable medium may include instructions whichrepresent various logic within the processor. When read by a machine,the instructions may cause the machine to fabricate the logic to performthe techniques described herein. Such representations, known as “IPcores,” are reusable units of logic for an integrated circuit that maybe stored on a tangible, machine-readable medium as a hardware modelthat describes the structure of the integrated circuit. The hardwaremodel may be supplied to various customers or manufacturing facilities,which load the hardware model on fabrication machines that manufacturethe integrated circuit. The integrated circuit may be fabricated suchthat the circuit performs operations described in association with anyof the embodiments described herein.

FIG. 16 is a block diagram illustrating an IP core development system1600 that may be used to manufacture an integrated circuit to performoperations according to an embodiment. The IP core development system1600 may be used to generate modular, re-usable designs that can beincorporated into a larger design or used to construct an entireintegrated circuit (e.g., an SoC integrated circuit). A design facility1630 can generate a software simulation 1610 of an IP core design in ahigh level programming language (e.g., C/C++). The software simulation1610 can be used to design, test, and verify the behavior of the IPcore. A register transfer level (RTL) design can then be created orsynthesized from the simulation model. The RTL design 1615 is anabstraction of the behavior of the integrated circuit that models theflow of digital signals between hardware registers, including theassociated logic performed using the modeled digital signals. Inaddition to an RTL design 1615, lower-level designs at the logic levelor transistor level may also be created, designed, or synthesized. Thus,the particular details of the initial design and simulation may vary.

The RTL design 1615 or equivalent may be further synthesized by thedesign facility into a hardware model 1620, which may be in a hardwaredescription language (HDL), or some other representation of physicaldesign data. The HDL may be further simulated or tested to verify the IPcore design. The IP core design can be stored for delivery to a thirdparty fabrication facility 1665 using non-volatile memory 1640 (e.g.,hard disk, flash memory, or any non-volatile storage medium).Alternately, the IP core design may be transmitted (e.g., via theInternet) over a wired connection 1650 or wireless connection 1660. Thefabrication facility 1665 may then fabricate an integrated circuit thatis based at least in part on the IP core design. The fabricatedintegrated circuit can be configured to perform operations in accordancewith at least one embodiment described herein.

Referring now to FIG. 17, shown is a time diagram illustrating processorpower control in accordance with an embodiment of the present invention.As shown in FIG. 17, a curve 1700 is a graphical representation ofpower/frequency of a processor versus time. As illustrated, after aninitial idle period 1705, a processor exits a given low power state at amaximum performance level, generally illustrated at a point 1710 incurve 1700. It is understood that some delay between a low power stateexit and responsive time may occur for the purpose of workloadcharacterization or performing algorithmic computations. During thismaximum performance level phase, a user perceived responsivenessworkload may begin execution. Although the scope of the presentinvention is not limited in this regard, this responsiveness performancelevel phase 1710 may occur for between approximately 100 milliseconds(ms) to approximately 10 second, in some embodiments. After this timeduration, control automatically causes the processor to execute in along burst performance level phase 1720, which is at an intermediateperformance level. Understand that the length of long burst performancelevel phase 1720 may depend on availability of a relevant budget. Indifferent examples, this long burst phase may occur for betweenapproximately 10 and 60 seconds. Then, when the available budget isexhausted, the processor may be controlled to enter into a sustainedperformance level phase 1730, in which processor operation may continueat a lower performance level. The expected length of the maximum andintermediate levels may also be explicitly communicated to the powercontrol unit, e.g., via a machine specific register, or memory mappedinput output, among others. Furthermore, length can be predicted basedon history (e.g., statistics) or application type (media playback,graphical user interface (GUI), etc.). Understand while shown with thisparticular illustration in FIG. 17, many variations and alternatives ofprocessor control are possible.

Referring now to FIG. 18, shown is a time diagram illustrating processorpower control in accordance with another embodiment of the presentinvention. As shown in FIG. 18, a curve 1800 is a similar graphicalrepresentation of power/frequency versus time as in FIG. 17. Howeverhere, after an initial idle period 1805 and a maximum performance levelphase 1810, an adaptive burst performance level phase 1820 occurs inwhich operation iteratively proceeds at multiple intermediateperformance levels, e.g., according to an adaptive technique. Thisadaptive control may be based on controlled exponential decay, userinteraction activity and/or expected length of workload. Then, when theavailable budget is exhausted, the processor may be controlled to enterinto a sustained performance level phase 1830.

In an example embodiment, controlling higher performance states canoccur in part based on multiple time durations, also referred to hereinas Tau values. These Tau values, of which there may be one or moreconfigured values for a given processor, provide a time scale for whichoperation is allowed to exceed certain power levels for which aprocessor may be configured. A first power limit may be a thermal designpower (TDP) level (also referred to as power limit 1 or PL1), which is along term average power consumption level that the processor is not toexceed (although it may exceed this level for certain time durations).This TDP level may thus be a sustained power level that the processor atwhich the processor can freely operate. Although this long term averageis not to be violated, operation can exceed the TDP level, assuming noprocessor constraints (e.g., electrical, thermal and/or power) areactive.

A second power limit may be set at a higher power level, which is alevel higher than the TDP level as may be set based on systemlimitations such as system power supply or voltage regulator and isreferred to herein as a power limit 2 (or PL2). The processor may safelyoperate at this higher performance level for a shorter time durationsuch as a given Tau value. Note that this PL2 may correspond to ahighest performance level such as a P0 performance state having amaximum turbo mode frequency. As described herein, when a processorexits an idle state to handle a responsiveness workload, it may directlybe placed into this P0 performance state and operate at the PL2 limit(or potentially even higher). That is in some implementationsinstantaneous processor operation may exceed PL2 to a higher, electricalpower level for a short duration, referred to as PL3, which is a maximumpower limit above which a system voltage regulator may cause animmediate fail situation.

In embodiments described herein, in addition to a TDP power level andone or more higher power levels such as PL2 and/or PL3, a processor maybe configured to operate in one or more intermediate power levelsbetween a maximum performance level and a sustained, e.g., TDPperformance level. More specifically as described herein, embodimentsmay provide for at least one intermediate performance level between PL2and PL1, such that after an initial burst to a maximum performance levelresponsive to waking from an idle state for handling a responsivenessworkload, the processor may be controlled to enter into thisintermediate performance state at which it may operate until a relevantbudget (e.g., thermal or power/energy budget) is consumed. Thereafter,operation may continue at the sustained, e.g., TDP power level.

In other embodiments, an adaptive technique that may be provided toenable the processor to operate at multiple intermediate performancelevels between a maximum performance level and a sustained performancelevel. To this end, embodiments may configure a processor with one ormore time durations and/or exponential decay values to cause theprocessor to first operate at a maximum performance level after exitingan idle state to handle a responsiveness workload, and thereafter tooperate at the multiple intermediate performance levels until therelevant budget or budgets are consumed. Thus in various embodiments, apower controller may be configured to enable certain tasks, whether userfacing and/or very short time scales, to exceed general power thermalbudgeting, tracking, and/or control limits that are otherwise appliedfor other workloads and/or time scales.

As described above, embodiments enable control of intermediateperformance states in different manners. In some cases, instead of afixed sustained decay arrangement (as in FIG. 17), an exponential decaymay be used, as in FIG. 18. In one particular embodiment, thisexponential decay may be according to Equation 1:P(n+1)=P1+((P(n)−(P1)*Kd. [Equation 1] In Equation 1, a performancestate (P) for a next time interval (P(n+1)) may be determined withreference to a current performance state (P(n)), a guaranteedperformance state (P1), and a predetermined constant Kd (which may beset to be a value less than 1). With this Equation (and selection of anappropriate constant), an exponential decay function is realized thatcauses an exponential decay from a current performance state through oneor more intermediate power states, and finally to a sustained powerstate. Furthermore, the intermediate point can be a function of externalreading of sensors such as system skin (outer surface) temperature.

To this end, a processor may include various configuration storages tostore control information for enabling this responsiveness performancecontrol. As examples, multiple configuration storages may be provided tostore the time durations associated with the maximum power level and oneor more intermediate power levels. In addition, configuration storagesmay be provided to store configured values for the maximum power leveland one or more intermediate power levels, along with the sustainedpower level. Still further, a processor may include hardware controlcircuitry to determine budget levels and enable the processor controldescribed herein to cause the processor to exit an idle state at amaximum performance level, then proceed through one or more intermediatepower levels until a relevant budget or budgets are consumed, andthereafter enter into a sustained performance state.

Control of a performance level (e.g., operating frequency and/oroperating voltage) for intermediate points may balance differentconsiderations. For example, if this intermediate performance leveloccurs with a too high frequency sub-optimal performance may occur for along workload. In contrast, operation at a too low frequency in thisintermediate performance level may fail to use an entire budget forshort bursts. As such, with the adaptive control as shown in FIG. 18,operation starts high and exponentially decays as workload timelengthens. Note that if there is a pause in execution of the workload(such as a context switch to another process, entry into an idle stateor so forth), when the workload then continues operation may begin againat the maximum performance level. Using embodiments as described herein,improved user perceived responsiveness and benchmark scores may berealized for burst workloads, including long burst workloads.Applications having short bursts may be user interactive workloads onGUI, web browsing and performing interactive photo editing. Benchmarksthat show it include Sysmark, WebEX touchEX etc., and long applicationsmay include video encoding, 3D gaming, SPEC, etc.

In an embodiment, a hardware P-state technique may be used to initiateentry into a maximum performance state at the beginning of aresponsiveness workload. Note that during operation, utilization may betracked (such as by way of active state residency counters or the like).In addition, by providing multiple timers for identifying utilizationtrends, short interrupts may be filtered out (e.g., increased activitylevels for less than approximately 5 ms) and a beginning of a burstphase (active period after an idle state) can be identified. Stillfurther, a repeating frame-based workload can be identified. For suchworkloads, for example, a DVD playback application, embodiments maycontrol operation such that there is no burst at the beginning of eachframe.

Referring now to FIG. 19, shown is a block diagram of a system inaccordance with an embodiment of the present invention. As shown in FIG.19, a system 1900 includes a processor 1910 coupled to a storage unit1960. In various embodiments, processor 1910 may be a multicoreprocessor, other type of SoC, or graphics or media processor. In turn,storage unit 1960 may be a given type of non-volatile storage, such as aflash memory, phase change memory, disk drive or other mass storage. Inother implementations, storage unit 1960 may be a volatile memory, suchas a system memory. In any event, understand that storage unit 1960 maystore one or more of a BIOS and OS, which may store user preferencesettings, including settings for balancing power and performance.

As illustrated, processor 1910 includes a plurality of cores 1905 ₀-1905_(n). Such cores 1905 may be a set of homogeneous cores, or one or moreof the cores may be heterogeneous cores. As an example, a mix of lowpower, e.g., in-order cores, and higher power, e.g., out-of-order cores,may be provided. To perform power control, including dynamic speedshifting as described herein, a power control unit 1920 couples to aP-state control logic 1950. Responsive to control information from PCU1920, P-state control logic 1950 may provide control signals toindependently control a performance state of each of cores 1905 ₀-1905_(n). Such control signals include frequency control signals and/orvoltage control signals to enable each of the cores to operate withpotentially independent and different voltage and frequency operatingparameter points. In some cases, the voltage control signals instead maybe provided to corresponding voltage regulators (not shown for ease ofillustration in FIG. 19) that provide the requested voltage to thecores. In some embodiments, control logic 1950 can be a combination ofhardware and software executed on the main processor (e.g., a processordevice driver such as an Intel® Device Platform and Thermal Framework(DPTF)).

In embodiments described herein, responsive to an exit from an idlestate to handle a responsiveness workload, PCU 1920 may control P-statecontrol logic 1950 to cause one or more cores to enter into a maximumperformance state (e.g., corresponding to a maximum turbo modefrequency). After an initial period of such maximum performanceoperation, the given one or more cores can be controlled to slowly decayperformance level down to a sustainable performance level (e.g.,corresponding to a TDP performance level).

As described herein, various information may be used to control suchoperation. More specifically as shown in FIG. 19, PCU 1920 may receiveinformation from a power budget and usage profiler 1930. In turn,profiler 1930 receives power information (such as energy consumptioninformation) from a power meter 1935. Although shown as a separate unitin the embodiment of FIG. 19, in some cases each core may include or beassociated with an independent power meter to provide energy consumptioninformation and/or other power information to profiler 1930. Inaddition, profiler 1930 receives residency information from one or moreC-state residency counters 1940. In some cases, a single residencycounter may be provided to count clock cycles in which at least one core1905 is in an active state. In other cases, multiple counters 1940 maybe provided, each associated with a given core, to count a number ofclock cycles in which the corresponding core is in an active state. Inanother embodiment, the information can be processor and SoC junctiontemperature, system skin temperature or other temperature sensors.

As further illustrated, profiler 1930 also receives information from asetting and preference control logic 1945. In various embodiments,information received from logic 1945 may include user preferenceinformation, such as one or more values to indicate a user preference,e.g., on a scale between a power biased preference and a performancebiased preference. In one embodiment, this information may be receivedfrom an OS based on user configuration of a system for high performance,power savings, or a balanced mode there between. Additional preferenceinformation may include various configuration information regardingcontrol parameters to be used, e.g., as time durations for variousphases of execution after exit from an idle state, e.g., a firstduration for a maximum responsiveness performance state, a secondduration for a higher performance state, along with configuration valuesfor various budgets, including power and thermal budgets. Understandwhile shown at this high level in the embodiment of FIG. 19, manyvariations and alternatives are possible.

Referring now to FIG. 20, shown is a flow diagram of a method inaccordance with an embodiment of the present invention. As shown in FIG.20, method 2000 may be performed by appropriate combinations ofhardware, software, and/or firmware, such as a hardware power controllogic as described herein, which may be implemented as part of a powercontroller, itself implemented as one or more microcontrollers.

As seen, method 2000 begins by obtaining utilization information (block2010). Such utilization information may include, in an embodiment,information regarding activity in the processor, such as active stateresidency levels for the processor as a whole (or individually for oneor more cores of the processor), a number of active cores, user behaviorinformation or so forth. Next at block 2020, a power budget may bedetermined. Although described as a power budget, in some cases anenergy budget instead may be determined. As an example, such budget maybe determined as a difference between a configured maximum power/energyvalue that the processor can consume and a measure of the actualpower/energy consumed. In other cases a temperature budget instead maybe determined. Note even if this budget is exhausted, it is stillpossible to operate at highest performance levels for user facing tasks(and/or short time scales within other tuned limits). That is, differentbudgeting criteria and/or limits can be applied to different time scalesand/or workloads/tasks.

Next it can be determined at diamond 2030 whether the budget exceeds athreshold budget. In an embodiment, this threshold budget may be set ata value of zero. So long as there is available budget, namely that adifference between a measured activity level (e.g., by way of power,energy or so forth) exceeds the threshold budget, control next passes todiamond 2040 to determine whether a responsiveness workload has begun.Such responsiveness workload may be responsive to a user interactionwith a system, such as by way of touch input keyboard input, gestureactivity or so forth. In an embodiment, this determination may be madewhen an external interrupt is received (e.g., user interaction with thesystem, an incoming communication from an external source or so forth).

Still referring to FIG. 20, if a responsiveness workload is determinedto have started, control passes to block 2050 where the power controllermay set operation at a maximum turbo frequency. As an example, to handlethe workload the power controller may cause one or more (or all) coresto operate at a maximum performance state, e.g., at a maximum turbo modefrequency, which in an embodiment may correspond to a P0 performancestate. In some cases, depending upon the number of cores activated, thefrequency for this turbo mode may vary, such that with fewer coresactive, a higher turbo mode frequency can be set. Thereafter, at block2060 an attack timer may be set. This attack timer or other metric (suchas power budget) corresponds to a configured duration for the maximumperformance state. As an example, a configuration register may store amaximum value of this attack timer.

Still with reference to FIG. 20, next it can be determined whether theattack timer has expired or the available budget has been whollyconsumed (diamond 1870). Responsive to a determination of expiration ofthe timer or budget, control passes to block 2080 where a sustainedperformance state can be set. In embodiments, this sustained performancestate may correspond to a performance level at which the processor canoperate for long durations while maintaining operation within TDP levelson average over time.

Understand while shown at this high level in the embodiment of FIG. 20,many variations and alternatives are possible. For example, in someembodiments multiple attack timers can be provided to enable adaptivecontrol such that a processor may step in a smoother manner from amaximum performance state at the beginning of a responsiveness workload,to an intermediate power state which it may sustain for an intermediatetime duration, before controlling performance to drop to a sustainedperformance level. With this arrangement, the processor may operate forlonger durations after waking from an idle state to handle aresponsiveness workload before an opportunistic budget is consumed. Andin still other embodiments, multiple intermediate performance statesbetween a maximum responsiveness performance state and a sustainedperformance state are possible. Still further, understand that insteadof controlling transition of performance states by way of timers, inother cases different types of exponential controls such as exponentialdecay functions may be used. Furthermore, understand that processorconstraints in addition to power/energy budget such as thermal budgetsand so forth may be considered in controlling performance states atintermediate levels between a maximum performance state level and asustained performance state level. Note that various budgeting,tracking, and control parameters and/or priorities, may be changeable asdefined by the processor/component/device designer, and/or the systemdesigner, and/or the user.

The following examples pertain to further embodiments.

In one example, a processor includes: at least one core to executeinstructions; and a power controller coupled to the at least one core,the power controller including a first logic to cause the at least onecore to exit an idle state and enter into a maximum performance statefor a first time duration, thereafter enter into an intermediate powerstate for a second time duration, and thereafter enter into a sustainedperformance state.

In an example, the first logic is to cause the at least one core tooperate in the intermediate power state until a first budget isconsumed, and thereafter to cause the at least one core to enter intothe sustained performance state.

In an example, one or more of the first budget, the first time durationand the second time duration are configurable.

In an example, the intermediate power state comprises a plurality ofintermediate performance states, where the at least one core is tooperate in the plurality of intermediate performance states until thefirst budget is consumed.

In an example, the first logic is to determine the plurality ofintermediate performance states according to an exponential decayfunction.

In an example, the processor of one or more of the above examplesfurther includes a power meter to measure energy consumed by the atleast one core.

In an example, the first logic is to determine the first budget based atleast in part on a second power limit of the processor and the measuredenergy consumed by the at least one core.

In an example, the first logic is to cause the at least one core to exitthe idle state and enter into the maximum performance state to execute aresponsiveness workload, where a software agent is to identify theresponsiveness workload.

In an example, the processor further includes an architectural interfaceto enable the software agent to identify an application as having theresponsiveness workload.

In an example, the processor of one or more of the above examplesfurther includes: a first configuration register to store a value of thefirst time duration; and a second configuration register to store one ormore operating parameters of the maximum performance state.

Note that the above processor can be implemented using various means.

In an example, the processor comprises a SoC incorporated in a userequipment touch-enabled device.

In another example, a system comprises a display and a memory, andincludes the processor of one or more of the above examples

In yet another example, a method comprises: causing at least one core ofa processor to exit a low power state, responsive to identification of aresponsiveness workload to be executed; causing the at least one core toexit the idle state and directly enter into a maximum performance statefor a first duration; after the first duration, causing the at least onecore to enter into a second performance state until a first budget isconsumed, the second performance state greater than a sustainedperformance state; and after the first budget is consumed, causing theat least one core to enter into the sustained performance state.

In an example, the second performance state comprises a plurality ofintermediate power states.

In an example, the method further comprises determining a first one ofthe plurality of intermediate power states for a next interval based ona first performance state, a current performance state and a coefficientvalue.

In an example, the first performance state comprises a guaranteedperformance state and the coefficient value is to cause an exponentialdecay from the current performance state to the first intermediate powerstate.

In an example, the method further comprises setting the first durationto ensure that at least a portion of the first budget is available afterthe first duration.

In an example, the method further comprises causing the at least onecore to operate in the plurality of intermediate power states comprisingprogressively lower performance states.

In an example, the method further comprises: pausing execution of theresponsiveness workload during execution in the second performancestate; executing a second workload; and switching back to executing theresponsiveness workload at the maximum performance state.

In an example, the method further comprises: identifying a secondworkload comprising a frame-based workload; and causing the at least onecore to operate at a performance state different than the maximumperformance state during the second workload.

In another example, a computer readable medium including instructions isto perform the method of any of the above examples.

In another example, a computer readable medium including data is to beused by at least one machine to fabricate at least one integratedcircuit to perform the method of any one of the above examples.

In another example, an apparatus comprises means for performing themethod of any one of the above examples.

In an example, a system comprises: a processor including a plurality ofcores and a power controller, responsive to identification of a userworkload, to cause at least a first core of the plurality of cores toexit an idle state and enter into a maximum performance state for afirst time duration indicated in a configuration register, thereafterenter into a plurality of intermediate power states according to anexponential decay function, and thereafter enter into a sustainedperformance state; and a dynamic random access memory coupled to theprocessor.

In an example, the power controller is to cause the at least first coreto operate in the plurality of intermediate power states until a budgetis consumed, and thereafter to cause the at least first core to enterinto the sustained performance state.

In an example, the processor further comprises a power meter to measureenergy consumed by the plurality of cores, and where the powercontroller is to determine the budget based at least in part on a powerlimit of the processor and the measured energy consumed.

In an example, the power controller is to identify the first workloadresponsive to an external interrupt received in the processor, theexternal interrupt associated with a user interaction with the system.

Understand that various combinations of the above examples are possible.

Embodiments may be used in many different types of systems. For example,in one embodiment a communication device can be arranged to perform thevarious methods and techniques described herein. Of course, the scope ofthe present invention is not limited to a communication device, andinstead other embodiments can be directed to other types of apparatusfor processing instructions, or one or more machine readable mediaincluding instructions that in response to being executed on a computingdevice, cause the device to carry out one or more of the methods andtechniques described herein.

Embodiments may be implemented in code and may be stored on anon-transitory storage medium having stored thereon instructions whichcan be used to program a system to perform the instructions. Embodimentsalso may be implemented in data and may be stored on a non-transitorystorage medium, which if used by at least one machine, causes the atleast one machine to fabricate at least one integrated circuit toperform one or more operations. Still further embodiments may beimplemented in a computer readable storage medium including informationthat, when manufactured into a SoC or other processor, is to configurethe SoC or other processor to perform one or more operations. Thestorage medium may include, but is not limited to, any type of diskincluding floppy disks, optical disks, solid state drives (SSDs),compact disk read-only memories (CD-ROMs), compact disk rewritables(CD-RWs), and magneto-optical disks, semiconductor devices such asread-only memories (ROMs), random access memories (RAMS) such as dynamicrandom access memories (DRAMs), static random access memories (SRAMs),erasable programmable read-only memories (EPROMs), flash memories,electrically erasable programmable read-only memories (EEPROMs),magnetic or optical cards, or any other type of media suitable forstoring electronic instructions.

While the present invention has been described with respect to a limitednumber of embodiments, those skilled in the art will appreciate numerousmodifications and variations therefrom. It is intended that the appendedclaims cover all such modifications and variations as fall within thetrue spirit and scope of this present invention.

What is claimed is:
 1. A processor comprising: at least one core toexecute instructions; and a power controller coupled to the at least onecore, the power controller including a first logic to cause the at leastone core to exit an idle state and directly enter into a maximumperformance state having a maximum frequency for a first time durationto execute a responsiveness workload in which user interaction with acomputer system including the processor occurs, thereafter enter into anintermediate performance state for a second time duration, andthereafter enter into a sustained performance state.
 2. The processor ofclaim 1, wherein the first logic is to cause the at least one core tooperate in the intermediate performance state until a first budget isconsumed, and thereafter to cause the at least one core to enter intothe sustained performance state, the intermediate performance stategreater than the sustained performance state.
 3. The processor of claim2, wherein one or more of the first budget, the first time duration andthe second time duration are configurable.
 4. The processor of claim 1,wherein the intermediate performance state comprises a plurality ofintermediate performance states, wherein the at least one core is tooperate in the plurality of intermediate performance states until thefirst budget is consumed.
 5. The processor of claim 4, wherein the firstlogic is to determine the plurality of intermediate performance statesaccording to an exponential decay function.
 6. The processor of claim 1,further comprising a power meter to measure energy consumed by the atleast one core.
 7. The processor of claim 6, wherein the first logic isto determine the first budget based at least in part on a second powerlimit of the processor and the measured energy consumed by the at leastone core.
 8. The processor of claim 1, wherein a software agent is toidentify the responsiveness workload.
 9. The processor of claim 8,wherein the processor further comprises an architectural interface toenable the software agent to identify an application as having theresponsiveness workload.
 10. The processor of claim 1, furthercomprising: a first configuration register to store a value of the firsttime duration; and a second configuration register to store one or moreoperating parameters of the maximum performance state.
 11. Anon-transitory machine-readable medium having stored thereoninstructions, which if performed by a machine cause the machine toperform a method comprising: causing at least one core of a processor toexit an idle state and directly enter into a maximum performance statefor a first duration, responsive to identification of a responsivenessworkload to be executed in response to a user interaction with themachine; after the first duration, causing the at least one core toenter into a second performance state until a first budget is consumed,the second performance state greater than a sustained performance stateand less than the maximum performance state; and after the first budgetis consumed, causing the at least one core to enter into the sustainedperformance state.
 12. The non-transitory machine-readable medium ofclaim 11, wherein the second performance state comprises a plurality ofintermediate performance states.
 13. The non-transitory machine-readablemedium of claim 12, wherein the method further comprises determining afirst one of the plurality of intermediate performance states for a nextinterval based on a first performance state, a current performance stateand a coefficient value.
 14. The non-transitory machine-readable mediumof claim 13, wherein the first performance state comprises a guaranteedperformance state and the coefficient value is to cause an exponentialdecay from the current performance state to the first intermediateperformance state.
 15. The non-transitory machine-readable medium ofclaim 11, wherein the method further comprises setting the firstduration to ensure that at least a portion of the first budget isavailable after the first duration.
 16. The non-transitorymachine-readable medium of claim 12, wherein the method furthercomprises causing the at least one core to operate in the plurality ofintermediate power states comprising progressively lower performancestates.
 17. The non-transitory machine-readable medium of claim 11,wherein the method further comprises: pausing execution of theresponsiveness workload during execution in the second performancestate; executing a second workload; and switching back to executing theresponsiveness workload at the maximum performance state.
 18. Thenon-transitory machine-readable medium of claim 11, wherein the methodfurther comprises: identifying a second workload comprising aframe-based workload; and causing the at least one core to operate at aperformance state different than the maximum performance state duringthe second workload.
 19. A system comprising: a processor including aplurality of cores and a power controller, responsive to identificationof a user workload comprising a responsiveness workload in response to auser interaction with the system, to cause at least a first core of theplurality of cores to exit an idle state and enter into a maximumperformance state for a first time duration indicated in a configurationregister, thereafter enter into a plurality of intermediate performancestates according to an exponential decay function, and thereafter enterinto a sustained performance state; and a dynamic random access memorycoupled to the processor.
 20. The system of claim 19, wherein the powercontroller is to cause the at least first core to operate in theplurality of intermediate performance states until a budget is consumed,and thereafter to cause the at least first core to enter into thesustained performance state.
 21. The system of claim 20, wherein theprocessor further comprises a power meter to measure energy consumed bythe plurality of cores, and wherein the power controller is to determinethe budget based at least in part on a power limit of the processor andthe measured energy consumed.
 22. The system of claim 19, wherein thepower controller is to identify the user workload responsive to anexternal interrupt received in the processor, the external interruptassociated with the user interaction with the system.